A RESTful url using Stripes. R

RESTful url may contain the content type with in the url string. For example: http://host/action/xml/bookmark. Here “xml” is content type, this content type can be changed to “text, json” or etc…

So following urls are valid too. http://host/action/text/bookmark, http://host/action/json/bookmark etc…

these days I am playing with “Stripes” web framework a lot. Those who didn’t get in touch with “Stripes” have a look on the following URL - http://stripes.mc4j.org, hope you will enjoy it.

stripes has fantastic flexibility, it enables a lot of customization. Now my tutorial will demonstrate how you can enable this url pattern, where your single “ActionBean” will be invoked on the following url patterns:

http://host/action/xml/bookmark, http://host/action/text/bookmark, http://host/action/json/bookmark etc…

My target audience:
Who has already been introduced with Stripes or those who are interested on stripes framework.

Routing plan:
Request Dispatch
[visitor] —  > http://host/action/xml/bookmark — > [web server] — > [Stripe servlet] — > [Custom Action resolver] — > [remove user defined content type “xml” and retrieve action bean]

Response Dispatch
[clean url (after removing content type)] — > http://host/action/bookmark — > [BookmarkActionBean] — > [Resolution] — > <  hello world/  >

Pre requisite:
Stripes servlet is configured and web context is up and running.

ActionBean code:
*  create an ActionBean, for example “BookmarkActionBean”

<  CODE  >

@UrlBinding(”/action/bookmark”)

public class BookmarkAction implements ActionBean {

    private final Log LOG = LogFactory.getLog(getClass());

    private ActionBeanContext mActionBeanContext;

    private String mContentType = “text/xml”;

    public void setContext(ActionBeanContext actionBeanContext) {

        mActionBeanContext = actionBeanContext;

        // retrieve user requested content type constant for example “text,json, xml”

        // convert consts to mime type “text, text/xml, application/JSON”

        mContentType = URLHelper.getMimeType(URLHelper.getContentType(getContext().getRequest().getPathInfo()));

    }

    public ActionBeanContext getContext() {

        return mActionBeanContext;

    }

    @DefaultHandler

    public Resolution save() {

        if (LOG.isDebugEnabled())

            LOG.debug( “storing bookmark object on the data store, ” +

                       “response content type is requested - ” + mContentType );

        return new StreamingResolution( mContentType, new StringReader(”< test/ >“) );

    }

}

<  /CODE  >

Description:
Here i have set our action on “/action/bookmark” url, but our user requested url pattern is “/action/< contentTypeConstants >/actionBean”

Look on the “setContext” method, I have added an extra line

mContentType = URLHelper.getMimeType(URLHelper.getContentType(getContext().getRequest().getPathInfo()));

now have a look on the URLHelper class.

public static String getContentType( String pRequestedUrl ) {

        String contentType = CACHED_URL_CONTENT_TYPE.get(pRequestedUrl);

        if (contentType == null) {

            contentType = DEFAULT_CONTENT_TYPE;

            Perl5Util util = new Perl5Util();

            if (util.match( REGEX_ACTION_CONTENT_TYPE, pRequestedUrl ))

                contentType = util.group(1)+”";

            CACHED_URL_CONTENT_TYPE.put( pRequestedUrl, contentType );

        }

        return contentType;

    }

This method is responsible to retrieve user requested content type constants.
for example “text, xml, json”

public static String getMimeType( String pContentType ) {

        // convert content type to MIME Type

        if (pContentType.equalsIgnoreCase(CONTENT_TYPE_CONST_XML))

            pContentType = CONTENT_TYPE_XML;

        else if (pContentType.equalsIgnoreCase(CONTENT_TYPE_CONST_JSON))

            pContentType = CONTENT_TYPE_JSON;

        return pContentType;

    }

This method is also converting constant to MIME content type.
For example “xml –> text/xml”

Now return to my base action bean. I have added the following method, which is defined as default handler.

@DefaultHandler
public Resolution save() {

        ….

        return new StreamingResolution( mContentType, new StringReader(”< test/ >“) );

    }

Here “mContentType” is repopulate when “setContext” is invoked.

ActionResolver code:
This is my action resolver.

public class NBookmarkSystemActionResolver extends NameBasedActionResolver {

     // ………   

    @Override

    public ActionBean getActionBean(ActionBeanContext pActionBeanContext, String pRequestedUrl) throws StripesServletException {

        String cleanUrl = URLHelper.getCleanUrl(pRequestedUrl);

        if (LOG.isDebugEnabled())

            LOG.debug( “user requested url - ” + pRequestedUrl + ” clean url - ” + cleanUrl);

        return super.getActionBean(actionBeanContext, cleanUrl);

    }

}

Now let’s have a look on “getCleanUrl” method.

public static String getCleanUrl( String pRequestedUrl ) {

        return pRequestedUrl.replaceAll(”/”+getContentType(pRequestedUrl),”");

    }

Custom ActionResolver configuration:

< filter  >

        < display-name  >Stripes Filter< /display-name  >

        < filter-name >StripesFilter< /filter-name >

        < filter-class >net.sourceforge.stripes.controller.StripesFilter< /filter-class >

        <� init-param >

            <� param-name >ActionResolver.UrlFilters<� /param-name >

            <� param-value >/WEB-INF/classes/<� /param-value >

        <� /init-param >

        <� init-param >

            < param-name >ActionResolver.PackageFilters< /param-name >

            < param-value >com.we4tech.nBookmarkSystem.service.webService/*< /param-value >

        < /init-param >

        < init-param >

            < param-name >ActionResolver.Class< /param-name >

            < param-value >com.we4tech.nBookmarkSystem.configuration.NBookmarkSystemActionResolver< /param-value >

        < /init-param >

    < /filter >

That’s all for today,

Hope you will enjoy stripes. Best of luck…